[Mac] Implement an active state for the avatar button

chrome/browser/ui/cocoa/profiles/avatar_button.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_UI_COCOA_PROFILES_AVATAR_BUTTON_H_
 #define CHROME_BROWSER_UI_COCOA_PROFILES_AVATAR_BUTTON_H_
 
 #import <Cocoa/Cocoa.h>
 
 #import "ui/base/cocoa/hover_image_button.h"
 
-// A subclass of HoverImageButton that sends a target-action on right click.
+// A subclass of HoverImageButton that sends a target-action on right click and
+// has an active state.
 @interface AvatarButton : HoverImageButton {
  @private
   SEL rightAction_;
 }
 
+// YES if the button is active. The button should only be active when the
+// avatar bubble is shown.
+@property(nonatomic, assign) BOOL isActive;
+
 // Sets the action that will be called when this button is right clicked.
 - (void)setRightAction:(SEL)selector;
 
 @end
 
 #endif //CHROME_BROWSER_UI_COCOA_PROFILES_AVATAR_BUTTON_H_